Nerve Stimulator Firmware Development

Project Description

The project undertaken was to develop all of the firmware for a microcontroller based nerve stimulator that included a key pad, LCD display, and two channels of pulse generator outputs. The design of the product was driven completely by the process of reducing the manufacturing cost while providing an extremely flexible and easy to use operator interface. The product also required some extremely sophisticated real time software features in order to provide jitter free timing waveforms that included dynamic pulse width modulation and frequency modulation.

Skills Required

The primary skill required for this project was the need to provide a systems engineering design for the way that the microcontroller firmware would provide all of its various capabilities: user interface, jitter free pulse train generation, and internal parameter storage / recall. This led to skills needed to model algorithms for feasibility and to properly document the design requirements and details prior to undertaking the actual code development.

The firmware developed for this product was done in Motorola 68HC05 type native assembly language. Motorola low cost development tools were utilized to produce and debug the firmware. Specific skills included MATHCAD for modeling design, VISEO for software flow charting, and a detailed knowledge of the “process requirements” in order to produce firmware that is compliant with FDA standards.

Services Used

Embedded Systems provided design documentation services for Software Requirements Specifications, Software Design Specifications, Software Implementation Documentation, and Test Plan Criteria Development. All documentation was developed in a manner that was compatible with the “Development Process” used by the customer to produced FDA certified medical devices.

The actual software coding and test was also provided by Embedded Systems on a completely turnkey basis in a manner so as not to disrupt the normal engineering activities at the customer site. Project progress was tracked via a status report system that provided weekly summaries of completed activities, in process development, and critical action items or issues.

Project Size

The project as described was 5 man months of effort.


A Medical Products Company.